[dagnabbitt]

I have installed my new 355 in a 1981 Chevrolet SWB, very happy with the engine itself but the new exhaust that has been installed has a consistent and very loud drone that occurs at 2000RPM, and again around 2500RPM. This drone has made the truck more or less undriveable. The muffler shop cannot figure it out, they have tried as of today four different brand name mufflers and cannot eliminate the issue.

Truck has brand new stainless exhaust coming off of 2.5 inch ram horns manifolds, going through a crossover and into dual mufflers (four different ones so far, like I said) then goes over rear axle and dumps at 45 degree angle. Dumps do not seem to be the issue since it drones even up in the air on the hoist.

Going to try the J pipe route, looking at that spreadsheet now.